Hazard-detection and avoidance systems will become an important asset for next-generation landing and exploration missions. To date, multiple studies into these systems were conducted to develop the methods needed and to demonstrate their performance in mainly software-based tests. Few studies were able to demonstrate the performance of the algorithm in hardware-in-the-loop tests, as these are usually difficult to set up and expensive to execute. In this paper, the hardware-in-the-loop testing of a stereo-vision based hazarddetection algorithm is presented. It was performed with the Testbed for Robotic Optical Navigation (TRON) at the German Aerospace Center (DLR) in Bremen, Germany. Since this testbed only allows for testing in a scaled environment, one of the challenging tasks was to design a scaled-down test set-up to represent a real-life lunar descent. The hardwarein- the-loop testing confirmed the results obtained during the earlier software-in-the-loop testing, that stereo vision can successfully be used for hazard detection during planetary descent.@en